B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 1/30 Status of the (g - 2)  Fermilab Project Lee Roberts Department of Physics Boston University

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 2/30 New Collaborators are welcome! proposal is at

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 3/30 To understand where we’re going, you have to understand where we’ve been. Muons: –born polarized –die with information on where their spin was at the time of decay –highest energy e - carry spin information Self-analyzing Muon Decay N A NA 2 =0.4

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 4/30 Spin Motion: difference frequency between  S and  C Count number of decay e - with E e ≥ 1.8 GeV 0 Since g > 2, the spin gets ahead of the momentum Dirac: where a is the anomaly,

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 5/30 e ± from  ± → e±  are detected Count number of e - with E e ≥ 1.8 GeV 400 MHz digitizer gives t, E

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 6/30 E821 at Brookhaven –superferric storage ring, magic ,  ± 1 ppm Our past a  Experiment: ss   = 64.4  s; (g-2):  a = 4.37  s; Cyclotron: t C = 149 ns

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 7/30 Pedestal vs. Time Near sideFar side E821: used a “forward” decay beam with  ≃ 1:1 large “flash” in the detectors at injection GeV/c Decay GeV/c This baseline limits how early we can fit data ≃ 80 m decay path

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 8/30 The magnetic field is measured and controlled using pulsed NMR and the free-induction decay. Calibration to a spherical water sample that ties the field to the Larmor frequency of the free proton  p. We measure  a and  p Use =   /  p as the “fundamental constant”

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 9/30 The ± 1 ppm uniformity in the average field is obtained with special shimming tools. 0.5 ppm contours

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 10/30 New value for (CODATA 2006/2008) (Rev. Mod. Phys. 80, 633 (2008)) Blind analysis

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 11/30 E821 achieved 0.54 ppm; e + e - based theory 0.49 ppm Hint is 3.2  Davier et al, arXiv: [hep-ph] n.b. the experimental point does not include the new value of

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 12/30- p. 12/68 Model UED The Snowmass Points and Slopes give benchmarks to test observables with model predictions Future? Present Muon g-2 is a powerful discriminator... no matter where the final value lands! SPS Definitions

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 13/30 Suppose the MSSM point SPS1a is realized and the paramaters are determined at LHC- sgn(  gives sgn(  ) LHC (Sfitter) Old g-2 New g-2   sgn (  ) difficult to obtain from the collider tan  poorly determined by the collider from D. Stöckinger from Dominik Stöckinger

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 14/30 E821 at Brookhaven –superferric storage ring, magic ,  ± 1 ppm P989 at Fermilab –move the storage ring to Fermilab, improved shimming, new detectors, electronics, DAQ, –new beam structure that takes advantage of the multiple rings available at Fermilab, more muons per hour, less per fill of the ring Fermilab a  Experiment:

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 15/30 Advantages of the magic  technique 3 rd generation (CERN, E821, Fermilab) –technique well understood –high intensity polarized muon beam –large storage ring has ample room for detectors, field mapping, etc. –muon injection shown to work –rates in detectors are “reasonable” with conventional technology –many ( g -2) cycles to fit over –large decay asymmetry –precision field techniques well understood need to improve monitoring and control, but path is straightforward, if challenging. –systematic errors well understood and can be improved Limit of this technique ≃ 0.07 to 0.1 ppm error

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 16/30 Why Fermilab? The existence of many storage rings that are interlinked permits us to make the “ideal” beam structure. –proton bunch structure: BNL ~5 X p/fill: effective rate 4.4 Hz FNAL p/fill: effective rate 18 Hz –using antiproton rings as an 900m pion decay line 20 times less pion flash at injection than BNL –0 o muons ~5-10x increase  /p over BNL –Can run parasitic to main injector experiments (e.g. to NOVA) or take all the booster cycles

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 17/30 Polarized muons delivered and stored in the ring at the magic momentum, GeV/c n Uses 6/20 batches*  parasitic to program n Proton plan up to AP0 target is almost the same as for Mu2e n Uses the same target and lens as the present p-bar program n Modified AP2 line (+ quads) n New beam stub into ring n Needs simple building near cryo services *Can use all 20 if MI program is off beam rebunched in Recycler 4 x (1 x ) p

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 18/30 The 900-m long decay beam reduces the pion “flash” by x20 and leads to 6 – 12 times more stored muons per proton (compared to BNL) Stored Muons / POT Flash compared to BNL parameterFNAL/BNL p / fill0.25  / p 0.4  survive to ring 0.01  at magic P 50 Net0.05

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 19/30 Building Design for Fermilab AP0 g-2

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 20/30 Stable 2.5’ thick reinforced floor, supported by 4’ diameter caissons down to bedrock; temperature controlled ± 2 o F (Much better than E821)

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 21/30 Upgrades at Fermilab New segmented detectors to reduce pileup –W-scifi prototype under study New electronics –500 MHz 12-bit WFDs, with deep memories Improvements in the magnetic field calibration, measurement and monitoring.

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 22/30 Complementary ways to collect data Event Method Geant simulation using new detector schemes “t” method – time and energy of each event - pileup

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 23/30 Complementary ways to collect data Event Method Geant simulation using new detector schemes Energy Method Same GEANT simulation “t” method – time and energy of each event - pileup “q” method – integrate the energy - no pileup

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 24/30 The error budget for a new experiment represents a continuation of improvements already made during E821 Systematic uncertainty (ppm) E821 final P989 Goal Magnetic field –  p Anomalous precession –  a Statistical uncertainty (ppm) Systematic uncertainty (ppm) Total Uncertainty (ppm)

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 25/30 Systematic errors on ω a (ppm) σ systematic Future Pile-up AGS Background * Lost Muons Timing Shifts E-Field, Pitch *0.03 Fitting/Binning * CBO Beam Debunching * Gain Change total ~0.07 Σ* = 0.11

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 26/30 The Precision Field: Systematic errors Why is the error 0.11 ppm? –That’s with existing knowledge and experience with R&D defined in proposal, it will get better Next (g-2)

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 27/30 Ring relocation to Fermilab Heavy-lift helicopters bring coils to a barge Rest of magnet is a “kit” that can be trucked to and from the barge Back

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 28/30 Sikorsky S64F 12.5 T hook weight (Outer coil 8T) from Chris Polly

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 29/30 Possible Schedule? CY 2009 –PAC proposal defended in March 2009 (Well received, but how many$?) –Laboratory supports costing exercise July-October –Report to PAC meeting November CY 2010 Approval? –building design finished –other preliminary engineering and R&D CY 2011 Tevatron running finishes in Oct. –building construction begins –ring disassembly begins FY2012 CY 2012 –building completed mid-year –ring shipped –re-construct ring –shim magnet late 2014 or early 2015 Beam to experiment –2 year data collection on  +

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 30/30 At present there appears to be a difference between a  and the standard-model e + e - based prediction at the 3.2  level, post BaBar. We have proposed to reduce the experimental error by a factor of 4 at Fermilab. Our goal is to clarify if there is a discrepancy between experiment and theory, but whatever happens a  will continue to be valuable in restricting physics beyond the standard model. It will be especially important in guiding the interpretation of the LHC data. Summary

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 31/30 A special thank you to our hosts! THE END

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 32/30 muon (g-2) storage ring Muon lifetime t m = 64.4 ms (g-2) period t a = 4.37 ms Cyclotron period t C = 149 ns

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 33/30 SPS points and slopes SPS 1a: ``Typical '' mSUGRA point with intermediate value of tan_beta. SPS 1b: ``Typical '' mSUGRA point with relatively high tan_beta; tau- rich neutralino and chargino decays. SPS 2: ``Focus point '' scenario in mSUGRA; relatively heavy squarks and sleptons, charginos and neutralinos are fairly light; the gluino is lighter than the squarks SPS 3: mSUGRA scenario with model line into ``co-annihilation region''; very small slepton-neutralino mass difference SPS 4: mSUGRA scenario with large tan_beta; the couplings of A, H to b quarks and taus as well as the coupling of the charged Higgs to top and bottom are significantly enhanced in this scenario, resulting in particular in large associated production cross sections for the heavy Higgs bosons SPS 5: mSUGRA scenario with relatively light scalar top quark; relatively low tan_beta SPS 6: mSUGRA-like scenario with non-unified gaugino masses SPS 7: GMSB scenario with stau NLSP SPS 8: GMSB scenario with neutralino NLSP SPS 9: AMSB scenario SPS PLOT Back

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 34/30 (g-2) at Fermilab: Costing study concluding this month. Coils have to be moved by helicopter and barge

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 35/30  a Systematic Error Summary

B. Lee Roberts, PHIPSI 2009, Beijing – 14 October p. 36/30 New value for (CODATA 2006/2008) (Rev. Mod. Phys. 80, 633 (2008)) an increase by 14% of the experimental error